I wrote an update for the offsite_payments gem (which I understood is somehow used by Shopify), regarding an HPP integration. It's basically updating realex to global payments.
I had to remap some of the fields and add some new ones as well. I managed to test that the fields are sent correctly by creating a simple ruby on rails application, but I don't know how to test it using a Shopify application.
Is there a way to install it locally and use my updated version of the gem?